1. Field of the Invention
The present invention relates to ink-jet printers, and in particular relates to an ink-jet printer for printing by discharging ink from a print head onto a recording medium which is stuck and transported in an image formation section.
2. Description of Related Art
Low price ink-jet printers capable of high-speed color printing have become remarkably popular. The ink-jet printer is coupled to a terminal of a personal computer or the like, acquires image data, such as a text, an illustration, and a symbol, prepared in this terminal, and prints this data onto a paper. Moreover, a complex ink-jet printer integrated with a scanner or a facsimile can print the image data acquired from a scanner unit or can print the image data transferred by the facsimile.
This type of ink-jet printer includes a mechanism for transporting a recording paper while sticking the same onto a platen plate in a position facing a print head of an image formation section. The recording paper is transported by a transport belt which slides on the platen plate, and is stuck to the platen plate via this transport belt using a suction force. By providing such a mechanism, in the image formation section the wrinkles or corrugations (cockling) of a recording paper can be prevented and also the curling of a recording paper can be prevented, and therefore the floating of a recording paper can be eliminated. As a result, the interference (e.g., recording-paper jam) between a recording paper and a print head can be prevented, and a distance (head gap) between a print head and a recording paper can be stably secured. Accordingly, a stable print and print image quality can be obtained.
In order to obtain a more stable print and print image quality, the suction force of a recording paper may be increased. However, with an increase of the suction force in the vicinity of a print head, air flow becomes fast and this air flow affects the orbit of an ink drop discharged from the print head, resulting in degradation in the print image quality. Moreover, as the air flow becomes fast, mist is likely to be induced from an ink drop and this mist results in dirt on a recording paper and results in contamination inside the ink-jet printer (contamination inside the device).
Japanese Patent Application Laid-open Publication No. 2007-31007 discloses a paper transport mechanism which is used in an ink-jet printer, includes an air flow control unit for controlling so as to reduce the air flow in a paper transport direction which occurs in the vicinity of an area directly under an ink-jet head, and can suppress the occurrence of the above-described ink mist. As the air flow control unit of this paper transport mechanism, an example of plugging an air flow hole on a platen, an example of reducing the formation density of air flow holes, and an example of reducing the diameter of the air flow hole are disclosed. By providing this air flow control unit, the paper contamination due to the ink mist generated in an end part of a paper can be prevented.